/*
 * Copyright (c) 2012, Fredrik Yttergren
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name LucidBot nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL Fredrik Yttergren BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package api.tools.collections;

import javax.annotation.Nullable;
import java.util.ArrayList;
import java.util.Collection;

public class CollectionUtil {
    private CollectionUtil() {
    }

    /**
     * @param col a collection
     * @return true if the specified collection is null or empty
     */
    public static boolean isEmpty(@Nullable final Collection<?> col) {
        Collection<?> colWithoutNulls = removeNulls(col);
        return colWithoutNulls.isEmpty();
    }

    /**
     * @param col a collection
     * @return true if the specified collection is non-null and not empty
     */
    public static boolean isNotEmpty(@Nullable final Collection<?> col) {
        return !isEmpty(col);
    }

    public static <E> Collection<E> removeNulls(@Nullable final Collection<E> col) {
        Collection<E> out = new ArrayList<>();
        if (col != null) {
            for (E object : col) {
                if (object != null) out.add(object);
            }
        }
        return out;
    }
}
